"A process through which the cross-sectional area of a metal piece is increased with a corresponding reduction in its length" is known as: 

Explanation:

Upsetting

• Upsetting is a forging process in which the cross-sectional area of a metal piece is increased by compressive forces, which results in a corresponding reduction in its length. This process is one of the fundamental metalworking operations and is widely used in the manufacturing industry to produce components such as bolts, rivets, and other fasteners.
• Upsetting involves applying compressive forces to a heated or cold workpiece, typically using a die or hammer. The material is plastically deformed, causing it to bulge or expand in a specific region. This deformation is achieved without compromising the integrity of the material, and the process is designed to achieve precise dimensional control.

Steps Involved in Upsetting:

1. Preparation: The workpiece is prepared by cutting it to the desired length and heating it to the appropriate temperature (if hot forging is used).
2. Positioning: The workpiece is placed in the die or between the hammer and anvil in the desired position.
3. Application of Force: Compressive force is applied to the end or middle of the workpiece, depending on the design requirements. This force causes the material to expand in the desired direction.
4. Finishing: The deformed workpiece is removed from the die, and any excess material is trimmed or machined to achieve the final shape.

Applications:

• Manufacturing of bolts, rivets, and other fasteners.
• Production of gear blanks and flanges.
• Creation of components for automotive, aerospace, and construction industries.